1. Field of the Invention
The present invention relates to a scanner, and more particularly, to a scanner having a controller for controlling movement of a scanning module during scanner maintenance.
2. Description of the Prior Art
Please refer to FIG. 1, which is a schematic diagram of a prior art scanner 10. The scanner 10 comprises a housing 12, a transparent platform 14 installed on the housing 12 for a document 16 to be placed thereon, a track 18 installed inside the housing 12, and a scanning module 20 installed on and able to slide along the track 18 for scanning the document 16 and for generating corresponding image signals. The scanning module 20 further comprises a light-emitting device 24 (such as a fluorescent light) for projecting light onto the document 16. The scanning module 20 also comprises a driving device 26 (shown as dotted lines) for driving the scanning module 20 back and forth along the track 18.
Please refer to FIG. 2 and FIG. 3. FIG. 2 is a top view diagram of the prior art scanner 10 shown in FIG. 1. FIG. 3 is a cross-sectional diagram along line 3—3 shown in FIG. 2. The scanner 10 also comprises a pair of hooks 22 installed inside the housing 12 and positioned at the same side as the home position. Whenever the scanning module 20 returns to the home position, the scanning module 20 always stays under the hooks 22. The scanning module 20 inlays itself into the hooks 22 from touching or even from destroying the transparent platform 14 during a delivery.
Please refer to FIG. 4, which is a partial bottom view diagram of the scanning module 20. The driving device 26 comprises a step motor (not shown) for turning an driving gear 28 around, a plurality of driven gears 30, 32 for transforming a high angular velocity of the driving gear 28 to a low angular velocity, a belt wheel 34, and a belt 36. The step motor turns the driving gear 28 around, which drives the driven gears 30, 32. The belt 36 of the driven gear 32 then spins the belt wheel 34 to drive the scanning module 20 to move back and forth along the track 18.
In general, the scanner 10 executes a setup process before it scans the document 16. After the scanner 10 has executed the setup process, the scanning module 20 stays at the home position under the hooks 22 (as shown in FIG. 3). When the scanner 10 is scanning the document 16, the driving device 26 drives the scanning module 20 to move along the track 18 from one end of the track 18 (home position) to the other end of the track 18 and drives the scanning module 20 to move backward along the track 18 until the scanning module 20 reaches the home position. If interrupted by a power failure or by an unexpected incident, the scanner 10 will still execute the setup process first after the power has recovered or the unexpected incident has been resolved. That is, no matter what position the scanning module 20 is in before the power interruption, the scanning module 20 will always move to the home position and stay there again after the scanner 10 has executed the setup process.
When a maintenance worker is about to disassemble the scanning module 20 from the scanner 10 or to repair some components inside the scanner 10, the maintenance worker has to push the scanning module 20 manually along the track 18 out from the hooks 22. However, because the gears 28, 30, 32 of the driving device 26 are designed as active driving elements (for the scanning module 20) and are hard to be driven passively, moving the scanning module 20 by hand is not always stable. Moving the scanning module 20 manually always reduces the accuracy of the scanning module 20 and even damages the driving device 26. Moreover, some driving devices of modern scanners are manufactured by a combination of worm gears and worm rods, so moving a scanning module of a scanner manually has become a difficult task.